The use of interchangeable display sign systems is widespread in a variety of retailing industries, and is especially prevalent in restaurant and similar establishments where various items and their prices are subject to change on a relatively frequent basis. In many restaurants, a display sign system is often arranged adjacent a service counter where items are ordered paid for, and delivered to the customer. Often these sign systems are backlighted with light sources mounted within the sign itself, while product and price information and similar indicia is provided as translucent characters and/or images on an otherwise opaque background, whereby the light passes through the characters and illuminates the information in contrast to its opaque surroundings.
Examples of illuminated display signs are seen in U.S. Pat. No. 3,742,633 which issued to Bernhard Palm and U.S. Pat. No. 3,458,945 which issued to L. N. Edwards. The Palm reference describes an illuminated display sign which includes individual characters which are placed between vertically spaced longitudinal rails. The rails are formed with a shallow channel in the lower rail and a deeper channel in the upper rail to enable insertion and removal of individual sign characters. In particular, removal is accomplished by sliding the sign character upwardly into the deeper channel of the upper rail until the character clears the upper portions of the lower rail, then pivoting the character inwardly toward the sign panel and sliding the lower end into the shallow channel in the lower rail. The insertion and removal of individual characters thereby requires a rather intricate set of manipulations, requiring additional labor and time to achieve sign changes. Moreover, this arrangement requires the use of a biasing means to maintain adjacent characters in a tight relationship to prevent leakage of light between the individual characters, making insertion and removal of those characters more awkward and inconvenient.
The Edwards reference describes a display sign having a plurality of longitudinal protuberances designed to receive clips which support display indicia, as shown in the earlier Edwards patent U.S. Pat. No. 3,315,392. Such a mounting system for indicia is not contemplated for use in backlighted applications, however, as light leakage between adjacent indicia characters would be unacceptable. Furthermore, the use of the protuberance/clip support arrangement for the indicia characters is unwieldy and inefficient for display signs having a relatively large amount of information and indicia characters to be supported.
U.S. Pat. No. 4,367,604, which issued to Steven T. Porter, II, on Jan. 11, 1983, is directed to a backlighted menu board which has a plurality of vertically spaced ribs on the outer surface of a sign panel, and discusses the use of information strips which are insertable between the ribs. These information strips are generally opaque and have transparent portions spelling out the name of the menu item which allow light to be passed therethrough. Porter further describes the provision of a plurality of picture display units which can be easily engaged with the flanges of two ribs of the sign, and which can be changed without dismantling a major portion of the sign. However, the Porter display sign requires its information strips to be printed or otherwise custom made for each menu item and price. Changing the information or price entails replacing the information strip with a new strip having the corrected information provided thereon. This arrangement is not only inconvenient, but can be expensive.
To overcome the problems associated with information strips which must be replaced with new strips when information is to be changed, prior art devices have also included a support strip or holder for a plurality of individual indicia characters which can be inserted and removed from the support strip. U.S. Pat. No. 4,682,430 which issued to Charles Ramsey on Jul. 28, 1987, is an example. The Ramsey patent shows a price chip support strip which provides access to the individual price chips through the upper portions of rectangular pockets provided therein. The strip itself supports a plurality of individual price chips (i.e. 5) by providing a series of price chip receptor pockets fixedly attached adjacent one another. The strip is designed to be inserted between a pair of guide tracks mounted on the rear surface of a transparent frame panel which is provided on its front face with an opaque mask which defines elongated clear panels for display of the price chip indicia held within the price chip support strip. However, it is necessary to withdraw the price chip support strip from the support frame tracks to obtain access to the individual price chips held there within. Consequently, additional labor is required when changes are desirable, as the price chip support strip must be removed from the sign system. Moreover, because the support tracks are located on the rear face of the sign panel, access to the rear of the sign is required, further complicating sign change procedures, and often requiring the sign to be partially dismantled or opened.
Similar problems are encountered in making changes to signs such as those disclosed in U.S. Pat. No. 4,693,026, which issued to D. Callahan et al. on Sep. 15, 1987, and U.S. Pat. No. 4,765,080, which issued to W. Conti on Aug. 23, 1988. Both of these changeable display devices require at least partial dismantling of the apparatus in order to change the information displayed thereon. As mentioned, because display signs of this type are often preferably mounted in close proximity to service counters and other areas critical to the operation of a restaurant or similar business, display signs requiring substantial labor and/or dismantling of the sign system are inefficient and obtrusive. Heretofore, the devices available in the industry have failed to provide a sign system which provides convenient access from the front of the sign panel for easy placement and changing of individual character indicia and other information which must be changed from time to time. Prior attempts to provide front access for changing of displayed information required complex structures and/or inconvenient manipulation of indicia elements and other sign components which complicated the sign modification procedures interfered with business operations, and added to the cost of operation through increased labor and capital outlays.